Pull-to-set blind rivets are set from one side of a workpiece to be riveted by inserting the flanged body of a blind rivet into a hole and collapsing the body of the rivet on the blind side of the hole by pulling on the projecting mandrel. The mandrel is gripped between the jaws of the setting tool and the pressure of grip required depends on a number of factors, including the ductility of the material of the rivet body and the hardness of the material used for the mandrel.
With improved technology, blind rivets are produced from much more difficult materials than hitherto, including mandrels made from very hard materials such for example as stainless steel. With hard material mandrels and less ductile rivet bodies, a much higher grip is required for the jaws of a setting tool if slipping is to be avoided.
It is accordingly an object of the present invention to provide a rivet-setting tool with gripping jaws with a reduced tendency to slip.
A gripping jaw for a rivet-setting tool is usually provided with a row of closely-spaced serrations, ridges or teeth in each of a pair of jaws which are applied symmetrically to the mandrel of a blind rivet. The teeth are usually provided at the rate of 30-40 teeth per inch so that a typical jaw 0.3 inch long has 10 or 11 teeth. When the tool is operated, the mandrel is gripped by the jaws and pulled into the blind end of the rivet body.